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How to finetune the emx driver?

Brasilio Castilho_1
Occasional Visitor

How to finetune the emx driver?

Hello all, I have connected an Alpha ES40 to an IBM Totalstorage DS4300 through one KGPSA-CA in fabric topology: great, perfect, lightspeed access! But... when I connect the second KGP (same configuration, same switch zone, as the first KGP): turtlespeed access...
Response time for a simple disklabel -r command grows from 0.1 seconds to 40 seconds. I don´t know where the problem cause is. Is the IBM driver replying to both KGP and the emx driver doesn´t know how to treat this?
Is it possible to tune the emx driver? Is there a compatibility problem between the two drivers (emx and DS4300)?
Any help?

KGPSA-CA driver 2.17, FW Rev 3.93a0 (2.40)
Tru64 5.1B-3.

Thanks a lot.
3 REPLIES
Hein van den Heuvel
Honored Contributor

Re: How to finetune the emx driver?

Doens't sound like 'fine tuning' is needed.
It is broken big time!

I'd be tempted to redo / reseat the fibre cabling.
Temporary disconnect the original, fast, path to see whether the new path works at all!
Temporary use the old cable to plug into the new adapter?

Are there any errors logged ( /var/adm/messages ) ?

How about 'hwmgr -show scsi -full -id xxx'
(check spelling)
Do all the paths makes sense?
Any stale paths / devices to clean up?

What does hwmgr know about each adapter?

And... sorry to suggest this... did you try a reboot?

If you need further help, then please consider attaching pertinent hwmgr output in a text file for a future reply, such that we have some details to talk about.

Cheers,
Hein.
Mark Poeschl_2
Honored Contributor

Re: How to finetune the emx driver?

Your driver and firmware versions are all current so that's not it. You mention that both KGPSAs are in the same zone. That's pretty unusual - normally they would not only be in different zones, but different fabrics. Is this a single switch configuration?

The emx driver in Unix has inherent multi-pathing capability so I doubt the problem is on that side. While there are tweaks one can make to the emx driver (sysconfig -q emx), it's really rare that you need to change them. I suspect it's an issue on the storage array. Is there something you can do on the DS4300 to enable/allow multi-path access?

Re: How to finetune the emx driver?

It's definitly not KGPSA/FW/SAN problem.
I have example 4 KGPSA connected to 2 different fabrics for EMC storages and EVAs.

One question: do You add DS4300 description to /etc/disktab ?